Control valve apparatus of power shovel

Abstract

A control valve apparatus includes a second-working-actuator acceleration control valve connected to a first working control valve in parallel. The second-working-actuator acceleration control valve includes pilot chambers receiving a pilot pressure for switching first and second working control valves and a flow channel that guides a pressure fluid of a first pump port to an entrance port side of the second working control valve. The second-working-actuator acceleration control valve is switchable between a first priority position in which a pressure fluid is guided to the first working control valve with a higher priority than the second working control valve and a second priority position in which a pressure fluid is guided to the second working control valve with a higher priority than the first working control valve.

The invention claimed is: 
     
       1. A control valve apparatus of a power shovel, comprising:
 a first hydraulic circuit system communicating with a first pump port connected to a first pump; 
 a second hydraulic circuit system communicating with a second pump port connected to a second pump; 
 a first working control valve provided in the first hydraulic circuit system to control a first working actuator; 
 a second working control valve provided in the second hydraulic circuit system to control a second working actuator; and 
 a second-working-actuator acceleration control valve provided in the first hydraulic circuit system and connected to the first working control valve in parallel, 
 wherein the second-working-actuator acceleration control valve includes
 a pair of pilot chambers, one of the pair of pilot chambers receiving a pilot pressure for switching the first working control valve, the other of the pair of pilot chambers receiving a pilot pressure for switching the second working control valve, and 
 a flow channel that guides a pressure fluid from the first pump port to an entrance port side of the second working control valve, and 
 
 the second-working-actuator acceleration control valve is switchable between
 a first priority position in which a pressure fluid is guided to the first working control valve with a higher priority than the second working control valve by virtue of the pilot pressure of the one pilot chamber, and 
 a second priority position in which a pressure fluid is guided to the second working control valve with a higher priority than the first working control valve by virtue of the pilot pressure of the other pilot chamber. 
 
 
     
     
       2. The control valve apparatus of the power shovel according to  claim 1 , wherein the second-working-actuator acceleration control valve includes a first flow restriction portion provided in the flow channel in a case of the first priority position and a second flow restriction portion provided in the flow channel in a case of the second priority position, and
 an opening rate of the first flow restriction portion is lower than that of the second flow restriction portion. 
 
     
     
       3. The control valve apparatus of the power shovel according to  claim 1 , wherein, in a case where the pilot pressure is applied to both the pilot chambers of the second-working-actuator acceleration control valve, the second-working-actuator acceleration control valve switches to a position between the first and second priority positions, where an effect of the pilot pressure of the one pilot chamber and an effect of the pilot pressure of the other pilot chamber are balanced. 
     
     
       4. The control valve apparatus of the power shovel according to  claim 1 , further comprising:
 a valve block including control valves of the first and second hydraulic circuit systems; 
 an auxiliary actuator port provided in the valve block and connected to an auxiliary actuator; and 
 an external line port connected to an external line, 
 wherein the second-working-actuator acceleration control valve is provided in a position inside the valve block the auxiliary actuator port and the external line port, and 
 the flow channel is connected to the entrance port side of the second working control valve via the external line port and the external line. 
 
     
     
       5. The control valve apparatus of the power shovel according to  claim 1 , wherein the second-working-actuator acceleration control valve is switchable to the first priority position, the second priority position, and an auxiliary position in which a pressure fluid is supplied to an auxiliary actuator, and
 the second-working-actuator acceleration control valve switches to a position between the first and second priority positions, where an effect of the pilot pressure of the one pilot chamber and an effect of the pilot pressure of the other pilot chamber are balanced.